Lubricants and power transmission fluids on the basis of carboxylic acid esters

ABSTRACT

A MIL 7808 lubricant and power transmission fluid comprising: 55 TO 70 WEIGHT PERCENT HEXANE-1, 6-DIOL-ISONONANOATEETHYLHEXANOATE; 15 TO 30 WEIGHT PERCENT 2,2-DIMETHYLPROPANEDIOL-PELARGONATENONANOATE; AND 10 TO 20 WEIGHT PERCENT OCTYL-NONYL-TRIMETHYLADIPATE.

United States Patent Giithel et al. July 4, 1972 [54] LUBRICANTS AND POWER [56] References Cited TRANSMISSION FLUIDS ON THE BASIS E OF CARBOXYLIC ACID ESTERS D STATES PATENTS 3,309,318 3/1967 Aylesworth et al ..252/56 S 1 Inventors: Herbert Gflhel, 0berhausen-Holten; Hans 2,548,493 4/1951 Robey ....252/56 s x Feichtinser, Dinslaken, both of Germany 3,048,542 8/1962 Tierney et al. .:...2s2/5s s x [73] Asslgneez glilrlr'glemle AG, Oberhausen-Holten, Primary Examiner Dani e1 E wy m a n Assistant Examiner-W. Cannon [22] Filed: May 13, 1970 Attorney-Burgess, Dinklage & Sprung [21] Appl. No.: 37,043 [57] ABSTRACT A M". 7808 lubricant and power transmission fluid compris- [30] Foreign Application Priority Data i May 16, 1969 Germany ..P 19 25 048.7 55 weigh Perm hexane'l ethylhexanoate; 52 U.S.Cl ..252/56 S,252/79,260/485 R 15 gg i f yjgi'ggfifif 22'd'methylpropaned'ol'pelar' 1 1m. Cl. g 58] Field of earch n 10 to 20 weight percent octyl-nonyl-tnmethyladlpate.

3 Claims, No Drawings LUBRICANTS AND POWER TRANSMISSION FLUIDS ON THE BASIS OF CARBOXYLIC ACID ESTERS Lubricating oils, especially those intended for use in subsonic jet propulsion aircraft engines as well as power transmission fluids for use under extreme temperature conditions,

must meet certain demands which are summarized for instance in USA Military Specification MILL-007808 F (socalled 7808 fluids). Oils corresponding to this standard specification must possess the following properties: viscosities above 3 cSt at 98.9C and below 13,000 cSt at 53.9C; flame points above 204C; and setting points below -60C. Furthermore they must meet certain demands with respect to corro sion as well as oxidation stability, which are likewise standardized.

Heretofore, esters of sebacic acid were generally used for this purpose (see Gunderson and Hart, Synthetic lubricants, New York, 1962, chapter 5 Dibasic acid esters).

Owing to the increasing requirements in high-grade lubricants and power transmission fluids, it is an object of the invention to provide ester-oils for use as lubricants, especially for turbine engines, as well as for power transmission fluids, which can economically be prepared in simple manner from easily obtainable, commercially available alcohol and acid components, which meet the hereinbefore-mentioned demands, particularly the 7808 specifications.

In accordance with the present invention it has now been found that these objects may be accomplished by lubricants and power transmission fluids, comprising 55 to 70 percent by weight hexane-l,6-diol-isononanoate-ethylhexanoate, 15 to 30 percent by weight 2,2-dimethylpropanediol-perlargonatenonanoate and to 20 percent by weight octyl-nonyltrimethyladipate.

Oils of the following composition possess especially valuable properties and are preferred: 60 to 65 percent by weight hexane-1,6-diol-isononanoate-ethylhexanoate, 20 to 24 percent by weight 2,2-dimethylpropanediol-pelargonatenonanoate and 13 to 17 percent by weight octyl-nonyltrimethyladipate.

Eachof these esters is derived from three different components. The esters derived from glycols are prepared by reaction thereof with two different monocarboxylic acids as specified. The ester of trimethyladipic acid is obtained by reaction of this acid with the two different mono-alcohol components. The esterification may be performed by any esterification process known in the art and is per se conventional.

1n the hexane-1,6-diol-isononanoate-ethyl-hexanoate, the acids should have a moiety mole ratio to each other, respectively, of about 0.9 to 1.1, preferably about equimolar proportions.

In the 2,2-dimethylpropanediol-pelargonate-nonanoate, the acids should have a moiety mole ratio to each other, respectively, of about 0.9 to 1.], preferably about equimolar proportions.

In the octyl-nonyl-trimethyladipate, the alcohols have a moiety mole ratio to each other, respectively, of about 0.9 to l 1 preferably about equimolar proportions.

The ester oil composition according to the invention is prepared by simple admixture of the esters in the appropriate specified quantities and including conventional additives as, for instance, oxidation inhibiting compounds or antifoaming agents as may be required or desired.

None of the individual components of the composition of this invention complies with the hereinbefore-mentioned requirements, as can be seen from the following. The ester 2,2 -dimethylpropane l ,3-diol-isononanoate-pelargonate for instance, which, owing to its quaternary carbon atom, is heat and oxidation resistant, possesses a viscosity of 10,200 cSt at -53 .9C, a setting point of70C, and a flame point of 208C, but its viscosity of 2.94 cSt at 989C ranges below the standard value of 3 cSt. The ester n-Oxo-octyl-n-Oxo-nonyltrimethyladipate, which, due to its structure, also exhibits thermal and oxidation stability, meets the said demands with a viscosity of 3.2 cSt at 989C, a flame point of 229C and a setting point of -69.0C but its viscosity of 17,100 cSt at -53.9C is higher than the standard value of 13,000 cSt. Hexane- 1 ,ti diol-isononanoate-ethy1hexa.noate satisfies requirements of viscosity of 3.17 cSt at 989C, of 11,800 at 53.9C; of setting point of -70C and of flame point of 217 C, but its heat and oxidation stability is less than that of the two other esters.

It was thus not to be expected that the admixture of the three hereinbefore-described individual components in the ratios according to the invention would yield an oil with excellent properties for the purposes specified.

EXAMPLE 1 A mixture was prepared from the following components:

7 63 percent by weight hexane-l,6-diol-3,5,5-trimethylhexanoate-2-ethylhexanoate 22 percent by weight 2,2-dimethylpropane-l,3-diol-pelargonate-3,5,5-trimethylhexanoate 15 percent by weight n-Oxo-octyl-n-Oxo-nonyl-2,2,4-

trimethyladipate.

The properties of this admixture are listed in the table. As is seen from these data, this composition corresponds to the MlL-L-007808 F specification.

The alcohol components of the esters according to the invention are derived from alcohols obtained by Oxo-synthesis and hydrogenation of the hydroformylation products. The expression n-Oxo" designates alcohols derived from alcohol mixtures obtained by hydroformylation of n-olefins (Oxosynthesis) followed by hydrogenation of the hereby-obtained aldehydes. This Oxo synthesis is per se well known.

The ester n-Oxo-octyl-n Oxo-nonyl-trimethyladipate has been hitherto not yet described. It is generally prepared in the manner described in Example 2.

EXAMPLE 2 A l0-liter round-bottom flask was charged with 2,356 g of trimethyladipic acid, 1,720 g of n-Oxo-octanol and 1,880 g of n-Oxo-nonanol. To said mixture were added 500 cm of cumene as entrainer, and 3 g of paratoluene-sulfonic acid as catalyst. The solution was heated for more than 5 hours with stirring under reflux, with the temperature maintained at 155C. During this time the theoretically formed amount of reaction water of 432 ml was carried out with the entrainer and separated with the aid of a laterally arranged water separator. Cumene was separated from the reaction product by distillation under the vacuum of a water-jet pump. Unreacted and only partially reacted components were separated from the cumene-frce reaction product in two fractions by vacuum distillation. A first fraction of 370 g, comprising the acid containing components, distilled over in a temperature range between 50 and 140C at 0.1 torr. A second fraction of 395 g was obtained in a temperature range between 110 and 154C at 0.002 torr. The distillation residue of 4,660 g represented the desired crude ester oil. Thus, the yield amounted to 91 percent. The neutralization number of the ester was about 0.1 mg KOH per g, the ester number was about 264 mg KOH per g. The crude ester product was distilled, under a vacuum of 0.001 torr, to a residue of g whereby the pure ester was obtained as a water-white product, which showed the following physical characteristics:

Flame point "C the TABLE Determined Standard value value Test (7808 Standards) (Example 1) Viscosity (DIN 51 562):

At 080 C Ar least 3.0 08!; e. 3.44 cSt. AI. 37.8 (LU. At least 11.0 cSt.. 13.49 081..

. l V Mitx. 13,000 cSL, 12,480 (:St.

i (A Mux. 'Hl% IZAMuHL. Fiumu mint (AH'IMD) xii.

760 ton V V V 4 4 V At least 204" (J t 223 C. l low point (ASTMD 97)-.." Below 60 (1 Below 67 (J. Evaporation less (ASTMD 972) (6% hrS., 204 C.) Max. 35% 30.6% by wt. Corrosionand oxidationstnbility (FTM 791a-5308 (72 hrs., 175 0.):

Ste 3:0.2 mgJcm. +0.04 rrigJern. Silver. =i=0.2 mg./cm. +0.07 mgJem. Copper- $0.4 mgJcm. +0.06 mgJcm. MgAl 6 :l=0.2 mg./cm. +0.05 rng./cm. g =i=O.2 mgJcm. +0.03 mgJem. Viscosity at 37.8 C. after aging (72 hrs., 175 C.) 5% to Below 1%.

Total acid number after aging (AS'IMD 664) (72 hrs., 175 C.).

Lead-corrosion (F'IM 791a- 5321) (1hr., 163 C). Max 6 mg./in. 1.27 mg./in. Silver-corrosion (FIM 701a- 5305) (50 hrs., 232 0,). 3.0 mgJin. 0.3 mgn/infl. Copper-corrosion (FIM 701a- 3.0 mg./in. 2.8 mg./in.

Max. 2.3 mg. KOH/g 0.24 mg. KOH/g.

5305) (50 hrS., 232 C.).

What is claimed is:

l. Lubricant or power transmission fluid comprising 55 to percent by weight hexanel ,6-diol-isononanoate-ethylhexanoate, 15 to 30 percent by weight 2,2-dimethylpropanediolperIargonate-3,5,5 trimethylhexanoate and 10 to 20 percent by weight octyl-nonyi-trimethyladipate.

3. Lubricant or power transmission fluid, as claimed in claim 1, wherein said hexane-l ,6-diol ester has an acid moiety mole ratio of about 0.9 to 1.1; said 2,2-dimethylpropanediol ester has an acid moiety mole ratio of about 0.9 to 1.1; and said trimethyladipate ester has an alcohol moiety mole ratio of about 0.9 to 1.1.

UNYFED STATES PATENT QFFHHE 'CERTEFICATE 0F CQRRECTEQN Patent No; 3,674,692 Dated July 471972 lnvento Herbert et a1 It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2 line 39 v "2,356" should be 2,256

C01. 3, TABLE At -53.9C the detetmined value is "12,489,? but it should be 12498;

C61; 3 TABLE "Flame Point (ASTMD)" should be Flame Point (ASTMD 92)--r Signed and sealed this 9th day of January 1973;

l sEAL EAttest:

i EDWARD M,FLETCHER,JR. ROBERT GOTTSCHALK ?Attesting-Officer Commissioner oi Patents FORM PO-105O (10 63) 

2. Lubricant or power transmission fluid, as claimed in claim 1, comprising 60 to 65 percent by weight hexane-1,6-diol-isononanoate-ethylhexanoate, 20 to 24 percent by weight 2,2-dimethylpropanediol-perlargonate-3,5,5 trimethylhexanoate and 13 to 17 percent by weight octyl-nonyl-trimethyladipate.
 3. Lubricant or power transmission fluid, as claimed in claim 1, wherein said hexane-1,6-diol ester has an acid moiety mole ratio of about 0.9 to 1.1; said 2,2-dimethylpropanediol ester has an acid moiety mole ratio of about 0.9 to 1.1; and said trimethyladipate ester has an alcohol moiety mole ratio of about 0.9 to 1.1. 